1. Field of the Invention
The present invention relates to a display device and a method used by the device, and more particularly, to an apparatus and a method to automatically calibrate a display device, which generate a pattern within the display device without connecting to external equipment.
2. Description of the Related Art
FIG. 1 is a block diagram of a conventional calibrating apparatus.
A PC-signal pattern generating signal 100 outside a display device generates standard signals (having a voltage range of 0V–700 mV), i.e., R, G, and B patterns. Also, a DTV signal pattern generating unit 110 outside the display device generates standard signals, i.e., Y, U, and V patterns.
An image board 120 carries out calibration using patterns generated by the PC signal pattern generating unit 100 or the DTV signal pattern generating unit 110. When the display device operates in a PC mode, a switch 120-1 switches to R, G, and B pattern signals. When the display device operates in a DTV mode, the switch 120-1 switches to Y, U, and V pattern signals.
A three-channel analog-to-digital converter (ADC) chip 120-2 is a calibration performing unit that carries out calibration. The calibration involves controlling gain and offset of a channel (three channels for the R, G, and B pattern signals or for the Y, U, and V pattern signals).
The three-channel ADC chip 120-2 converts the switched pattern signals (0V–700 mV in the case of PC signals) into 8-bit digital pattern signals ranging from 0V–255 mV. The minimum value and the maximum value among the converted digital pattern signals are stored in an internal register (not shown) of a scaler 120-3.
A micom 120-5 compares the minimum value and the maximum value among the converted digital pattern signals stored in the internal register (not shown) of the scaler 120-3 with a reference minimum value and a reference maximum value, respectively, stored in an electrically erasable programmable read-only memory (EEPROM) 120-4. The micom 120-5 outputs an offset adjusting signal to the three-channel ADC chip 120-2 to adjust the minimum value among the converted digital pattern signals to the reference minimum value 0V. Also, the micom 120-5 outputs a gain adjusting signal to the three-channel ADC chip 120-2 to adjust the maximum value among the converted digital pattern signals to the reference maximum value 255.
The three-channel ADC chip 120-2 adjusts the offset and gain of the digital pattern signals using the offset adjusting signal and the gain adjusting signal output from the micom 120-5.
U.S. Patent Publication No. 5,369,432 discloses an apparatus that calibrates the display device.
Conventionally, an external device must be directly connected to the display device to conduct the calibration, which requires human power. For automatic calibration, it is necessary to add a jig board to a signal cable, in which the occurrence of an overshoot and an undershoot degrades the quality of the calibration.
Also, as the automatic calibration progresses, special automatization equipment that controls a signal generator and an automatization remote controller are needed. In this case, in contrast to a case where a human performs calibration, the automization equipment cannot receive a signal indicating completion of the calibration from the display device, but proceeds with the calibration one-sidedly at a predetermined interval. As a result, when a calibration error occurs in a certain board, it is impossible to eliminate the calibration error.